ABSTRACT
Biological interactions, for example the interaction between an antibody and its antigen or between an enzyme and its substrate, are in most cases closely linked to the three-dimensional structure of the protein. Antibodies as well as enzymes are large (protein) molecules made up of long chains of amino acid whose sequence is predetermined by the genetic code. In addition, complex proteins may also contain sugar, lipid or phosphate groups. Proteins have many functions in living organisms. Enzymes are required for digesting food and thus supplying the organism with a usable form of energy. Antibodies constitute an important part of the molecular part of the immune system (humoral immune response). Bacteria, viruses and various toxins are marked as “foreign” by the means of such antibodies. The generation of antibodies seems to be almost unlimited in its diversity; in fact the immune system seems to be able to react with the formation of a suitable antibody to nearly every imaginable (natural and synthetic) antigen.
